ENVIRONMENTALLY BASED MATERNAL EFFECTS ARE THE PRIMARY FACTOR IN DETERMINING THE DEVELOPMENTAL RESPONSE OF GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) TO DIETARY IRON-DEFICIENCY

We investigated the inheritance of the developmental response of 2 lab oratory substrains of Lymantria dispar L. to dietary iron bioavailabil ity. The total phenotypic variance in instar at 10 d was higher for pr ogeny of parents reared on diet containing crystalline FePO4 than for progeny of parents reared on diet containing amorphous FePO4. regardle ss of the form of FePO4 used in the progeny diet or rearing site. The variability in developmental response of larvae to dietary iron bioava ilability was caused primarily by a nutritionally-based maternal effec t. Twenty-seven to 28% of the total phenotypic variance can be attribu ted to maternal effects when both parent and progeny are reared on iro n-deficient diet. The female parent's physiological response to diet q uality, specifically the amount of FePO4 in the amorphous form, determ ines the quantity or quality (or both) of the non-nuclear contribution she makes to her offspring. This contribution influences the potentia l for expression of genetic variation in iron requirements and phenoty pic plasticity. The estimated heritability of larval developmental rat e during the 1st 10 d was highest for those reared on diets deficient in iron. When both parents and progeny were reared on diet containing crystalline FePO4, 20-40% of the total variance was estimated to be ca used by additive genetic effects, compared with 6-15% when both genera tions were reared on diet containing amorphous FePO4. When dietary iro n is deficient for successive generations, it has many direct and indi rect effects on critical components of population growth that could in fluence the population dynamics of gypsy moth. The bioavailability of iron in foliage and factors that could affect it may play a role in th e population dynamics of gipsy moths.